Swash plate type variable displacement compressor

ABSTRACT

A compressor according to the present invention has a housing including a first and second cylinder bores. The inner diameter of the first cylinder bore is smaller than that of the second cylinder bore. In suction process, refrigerant gas is directly drawn from an inlet port into a first suction chamber. The refrigerant gas is flowed from the first suction chamber into a first compression chamber. In contrast, refrigerant gas is drawn through the inlet port, a first suction passage, the first suction chamber, a first communication passage, a swash plate chamber and a second communication passage and into a second compression chamber. According to the above-described compressor, wherein the inner diameter of the first cylinder bore is smaller than the second cylinder bore, the difference of the amplitude of the intake pulsation between the first compression chamber and the second compression chamber can be suitably reduced.

BACKGROUND OF THE INVENTION

The present invention relates to a swash plate type variable displacement compressor.

Japanese Patent Application Publication No. 1-219364 discloses a swash plate type variable displacement compressor (hereinafter referred to merely as “compressor”). The compressor has a housing that includes a front housing, a cylinder block and a rear housing. The front housing has therein a first suction chamber and a first discharge chamber. The rear housing has therein a second suction chamber, a second discharge chamber and a pressure control chamber.

The cylinder block has therein an inlet port, a swash plate chamber, a plurality of first cylinder bores, a plurality of second cylinder bores, and first, second, and third suction passages. The inlet port and the swash plate chamber are substantially formed at the center of the cylinder block. The inlet port is in communication with the external circuit. The first cylinder bores are formed on the front side of the cylinder block. The second cylinder bores are formed on the rear side of the cylinder block. The inner diameter of the first cylinder bores is the same as that of the second cylinder bores.

The first and second suction passages are formed in the cylinder block at positions adjacent to the first cylinder bore. The first suction passage is in communication with the inlet port and the first suction chamber. The second suction passage is in communication with the first suction chamber and the swash plate chamber. The third suction passage is formed in the cylinder block at a position adjacent to the second cylinder bore and in communication with the swash plate chamber and the second suction chamber.

A piston is reciprocally slidably received in each cylinder bore. Specifically, each piston has a first head reciprocally slidable in the first cylinder bore and a second head reciprocally slidable in the second cylinder bore. Since the inner diameter of the first cylinder bore is the same as that of the second cylinder bore, the outer diameter of the first head of the piston is the same as that of the second head. In this compressor, a first compression chamber is formed by the first cylinder bore and the first head and a second compression chamber is formed by the second cylinder bore and the second head. The first compression chamber is communicable with the first suction chamber and the first discharge chamber. The second compression chamber is communicable with the second suction chamber and the second discharge chamber.

Each piton has an opening and closing member that reciprocates with its corresponding piston. The reciprocating movement of the opening and closing member permits the inlet port to communicate with or be shut off from the swash plate chamber.

A drive shaft is inserted in the housing and rotatably supported by the cylinder block. A swash plate is mounted on the drive shaft for rotation therewith in the swash plate chamber. The swash plate is connected to each piston via a conversion mechanism. The conversion mechanism converts rotation of the swash plate into reciprocating movement of each piston in its corresponding cylinder bore for a stroke length that is determined by the inclination angle of the swash plate. A link mechanism is provided between the drive shaft and the swash plate for changing the inclination angle of the swash plate. The inclination angle is an angle that the swash plate makes with respect to the direction perpendicular to the axis of the drive shaft. The inclination angle is changed by an actuator that is controlled by a control mechanism.

The actuator is arranged in the swash plate chamber at a position on the second cylinder bore side of the swash plate. The actuator includes an actuator body and has a control pressure chamber. The actuator body has a support member and a spool. The support member is slidably mounted on the rear end of the drive shaft. The spool is provided between the cylinder block and the rear housing with the rear end of the spool disposed in the pressure control chamber. The spool is slidably supported by the cylinder block and the rear housing so as to slide back and forth in the cylinder block. A thrust bearing and a radial bearing are provided between the support member and the spool.

The link mechanism is so constructed that the top dead center position of the first head of the piston moves for a larger distance than that of the second head position with a change of the inclination angle of the swash plate. The link mechanism has a spherical support member, a concave spherical surface and a lug arm. The spherical support member is formed in the front end of the support member. The concave spherical surface is formed in the swash plate and encloses the spherical support member. The lug arm has a slit formed in the front surface of the swash plate and a plate part formed on the drive shaft. The plate part has therein an elongated hole extending in the plane perpendicular to the axis of the drive shaft and toward the axis of the drive shaft from the outer periphery of the compressor. The slit is swingably supported in the plate part via a pin inserted through the elongated hole. Thus, the swash plate is supported swingably with respect to the drive shaft.

In the compressor, when the control mechanism shut off the communication between the second discharge chamber and the pressure control chamber, the pressure in the control pressure chamber is as low as that in the swash plate chamber, so that the spool and the support member are moved backward. Therefore, the inclination angle of the swash plate is decreased and the stroke length of the piston is decreased, with the result that the compression capacity per rotation of the compressor is decreased. When the stroke length of the piston is thus small, the inlet port is shut off from the swash plate chamber by the opening and closing member. Therefore, refrigerant gas sucked from the inlet port is flowed through the first suction passage into the first suction chamber and then into the first compression chamber. In the second compression chamber, on the other hand, refrigerant gas sucked into the first suction chamber is flowed into the second suction passage, the swash plate chamber, the third suction passage and the second suction chamber in this order. In the compressor, wherein the top dead center position of the first head of the piston moves for a larger distance than that of the second head position, when the inclination angle of the swash plate is close to zero degree, the refrigerant gas is compressed slightly only in the second compression chamber and no compression is performed in the first compression chamber.

In the compressor, when the control mechanism makes communication between the second discharge chamber and the pressure control chamber, the pressure in the control chamber is higher than that in the swash plate chamber, so that the spool and the support member are moved forward. Therefore, the inclination angle of the swash plate is increased and the stroke length of the piston is increased, with the result that the compression capacity per rotation of the compressor is increased. When the stroke length of the piston is increased, the inlet port is made to be in communication with the swash plate chamber by the opening and closing member. Thus, not only the refrigerant gas sucked into the first suction chamber is flowed into the second compression chamber as described above, but also the refrigerant gas directly sucked into the swash plate chamber is flowed through the third suction passage into the second compression chamber.

Thus, in the compressor, the manner of sucking refrigerant gas into the first compression chamber is different from that into the second compression chamber. The stroke length of the piston is changed depending on the manner of sucking refrigerant gas. That is, flow rate of refrigerant gas sucked in the second compression chamber is varied according to the stroke length of the piston or according to the inclination angle of the swash plate.

In the conventional compressor described above, however, due to the difference in the manner of sucking refrigerant gas between the first compression chamber and the second compression chamber, the amplitude of the intake pulsation in the first compression chamber is different from that in the second compression chamber. This difference in the amplitude becomes more remarkable with an increase in the inclination angle of the swash plate and hence with an increase in the compression capacity. The intake pulsation that results from combining the intake pulsation of the first compression chamber and that of the second compression chamber is large and a noise may be generated, accordingly.

The present invention is directed to providing a swash plate type variable displacement compressor that is advantageous in terms of silence in operation.

SUMMARY OF THE INVENTION

A swash plate type variable displacement compressor forms a housing having therein a suction chamber into which refrigerant is drawn through an inlet port, a discharge chamber, a swash plate chamber and a cylinder bore, a drive shaft rotatably supported by the housing, a swash plate which is rotatable by the rotation of the drive shaft, a link mechanism provided between the drive shaft and the swash plate and allowing the swash plate to change the inclination angle of the swash plate to the direction perpendicular to the rotating axis of the drive shaft, a piston received to reciprocate in the cylinder bore, a conversion mechanism reciprocating the piston in the cylinder bore according to the inclination angle of the swash plate, an actuator allowing the swash plate to change the inclination angle of the swash plate and a control mechanism controlling the actuator. The cylinder bore includes a first cylinder bore provided in one surface side on the swash plate and a second cylinder bore provided in the other surface side on the swash plate. The piston includes a first head part that reciprocates in the first cylinder bore and forms a first compression chamber in the first cylinder bore and a second head part that reciprocates in the second cylinder bore and forms a second compression chamber in the second cylinder bore. The link mechanism is disposed so that the top dead center position of the first head part moves largely according to the change of the inclination angle of the swash plate as compared to the top dead center position of the second head part. The actuator includes an actuator body that is connected to the swash plate and movable in the direction of the rotating axis of the drive shaft and a pressure control chamber that moves the actuator body by changing the pressure of the pressure control chamber by the control mechanism. The swash plate type variable displacement compressor further includes a first suction flow passage through which the refrigerant is drawn through the inlet port into the first compression chamber, a second suction flow passage through which the refrigerant is drawn through the inlet port into the second compression chamber, a first suction valve mechanism provided in the first suction flow passage and a second suction valve mechanism provided in the second suction flow passage. The inner diameter of the first cylinder bore is smaller than that of the second cylinder bore. The compressor has at least either a structure in which the first suction flow passage is different from the second suction flow passage or a structure in which the first suction valve mechanism is different from the second suction valve mechanism so that the refrigerant is easily drawn through the inlet port into the first compression chamber as compared to the case in that the refrigerant is drawn through the inlet port into the second compression chamber.

Other aspects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention together with objects and advantages thereof, may best be understood by reference to the following description of the presently preferred embodiments together with the accompanying drawings in which:

FIG. 1 is a longitudinal sectional view of a compressor in maximum capacity according to a first embodiment of the present invention;

FIG. 2 is a schematic diagram showing a control mechanism of the compressor of FIG. 1;

FIG. 3 is a longitudinal sectional view of the compressor of FIG. 1 in minimum capacity;

FIG. 4 is a graph showing the relation between the rotation of a drive shaft and the intake pulsation in the case that the first suction passage and the second suction passage of the compressor of FIG. 1 are the same;

FIG. 5 is a graph showing the relation between the rotation of the drive shaft and the intake pulsation in the case that the first suction passage and the second suction passage of the compressor of FIG. 1 are different;

FIG. 6 is a longitudinal sectional view of a compressor in maximum capacity according to a second embodiment of the present invention;

FIG. 7 is an enlarged fragmentary view of the compressor of FIG. 6;

FIG. 8 is an enlarged fragmentary view of a compressor according to a third embodiment of the present invention;

FIG. 9 is an enlarged fragmentary view of a compressor according to a fourth embodiment of the present invention;

FIG. 10 is a longitudinal sectional view of a compressor in maximum capacity according to a fifth embodiment of the present invention;

FIG. 11 is a longitudinal sectional view of a compressor in maximum capacity according to a sixth embodiment of the present invention; and

FIG. 12 is a longitudinal sectional view of a compressor in maximum capacity according to a seventh embodiment of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The following will describe the embodiments according to the present invention with reference to FIGS. 1 through 7. Compressors according to the embodiments 1 through 7 of the present invention are swash plate type variable displacement compressors. The compressor is mounted on a vehicle and composes a part of cooling circuit for an air conditioner.

First Embodiment

Referencing to FIGS. 1 and 2, the compressor according to the first embodiment of the present invention includes a housing 1, a drive shaft 3, a swash plate 5, a link mechanism 7, a plurality of pistons 9, plural pairs of shoes 11A, 11B, an actuator 13 and a control mechanism 15.

As shown in FIG. 1, the housing 1 includes a rear housing 17, a front housing 19, first and second cylinder blocks 21, 23 disposed between the rear housing 17 and the front housing 19 and first and second valve forming plates 39, 41.

The aforementioned control mechanism 15 is provided in the rear housing 17. Furthermore, the rear housing 17 has therein a pressure control chamber 25, a first suction chamber 27A, a first discharge chamber 29A, an inlet port 170 and a first suction passage 171. The pressure control chamber 25 is positioned in the center part of the rear housing 17. The first discharge chamber 29A is formed in the rear housing 17 at a position adjacent to the outer periphery of the rear housing 17. The first suction chamber 27A is formed between the pressure control chamber 25 and the first discharge chamber 29A in the rear housing 17. Specifically, the first suction chamber 27A is formed at a position that is radially outward of the pressure control chamber 25 and radially inward of the first discharge chamber 29A.

A part of the first suction chamber 27A is formed extending rearward of the rear housing 17. The inlet port 170 is formed in the top of the rear housing 17. The first suction passage 171 and the first suction chamber 27A are integrally formed. The first suction passage 171 extends upwards and is in communication with the inlet port 170. Thus, the inlet port 170 is directly connected to the first suction chamber 27A and provides communication between an evaporator (not shown in the drawing) composing a part of the refrigerant gas circuit and the first suction chamber 27A.

The front housing 19 has at the front end thereof a boss 19A projecting forward. The boss 19A has therein a shaft seal device 31 disposed between the boss 19A and the drive shaft 3. The front housing 19 has therein a second suction chamber 27B and a second discharge chamber 29B. The second suction chamber 27B is formed in the front housing 19 adjacent to the center of the front housing 19. The second discharge chamber 29B is formed in the front housing 19 adjacent to the outer periphery of the front housing 19. The second discharge chamber 29B and the above-described first discharge chamber 29A are connected via a discharge passage (not shown in the drawing). The discharge passage has an outlet port (not shown in the drawing) that is in communication with the external circuit of the compressor.

The first cylinder block 21 and the second cylinder block 23 are adjoined each other between the rear housing 17 and the front housing 19. The first cylinder block 21 and the second cylinder block 23 are of substantially the same outer diameter. The first cylinder block 21 is positioned in a rear part of the compressor adjacently to the rear housing 17. On the other hand, the second cylinder block 23 is positioned in a front part of the compressor adjacently to the front housing 19. A swash plate chamber 33 is formed by and between the first cylinder block 21 and the second cylinder block 23 substantially in the longitudinal center of the compressor.

The first cylinder block 21 has therethrough a plurality of first cylinder bores 21A that are arranged at a regular angular interval and extending axially parallel to each other. The first cylinder block 21 also has therethrough a first shaft hole 21B through which the drive shaft 3 extends and that is in communication with the pressure control chamber 25. A first slide bearing 22A is provided in the first shaft hole 21B.

The first cylinder block 21 has therein a first accommodation chamber forming part forming a first accommodating chamber 21C that is in communication with and coaxial with the first shaft hole 21B. The first accommodating chamber 21C is enclosed by a wall forming a part of the first cylinder block 21 and separated from each first cylinder bore 21A. The first accommodating chamber 21C is in communication with the swash plate chamber 33. The first accommodating chamber 21C is of a stepped configuration having a larger inner diameter on the front side of the first accommodating chamber 21C and a smaller inner diameter on the rear side. The first accommodating chamber 21C has in the rear end thereof a first thrust bearing 35A. The first cylinder block 21 has therethrough a first communication passage 37A through which the first suction chamber 27A is in communication with the swash plate chamber 33.

The first cylinder block 21 has therein a first retainer groove 21E that adjustably determines the deflection of each first suction reed valve 391A which will be described later. That is, the first retainer groove 21E is provided in the first accommodation chamber forming part.

The second cylinder block 23 has therethrough a plurality of second cylinder bores 23A the number of which is the same as that of the above-described first cylinder bores 21A. The first cylinder bores 21A and the second cylinder bores 23A are coaxially formed. The inner diameter of the first cylinder bores 21A is smaller than that of the second cylinder bores 23A.

The second cylinder block 23 has therethrough a second shaft hole 23B through which the drive shaft 3 is inserted. A second slide bearing 22B is provided in the second shaft hole 23B. The second cylinder block 23 has therein a second accommodation chamber forming part forming a second accommodation chamber 23C that is in communication with and coaxial with the second shaft hole 238. The second accommodating chamber 23C is surrounded by a wall surface that is a part of the second cylinder block 23 and separated from each second cylinder bore 23A. The second accommodating chamber 23C is also in communication with the swash plate chamber 33. The second accommodating chamber 23C is of a stepped configuration having a smaller inner diameter on the front side of the second accommodating chamber 23C and a larger inner diameter on the rear side. A second thrust bearing 35B is provided in the front end of the second accommodating chamber 23C.

The second cylinder block 23 has therethrough a second communication passage 378 through which the second suction chamber 27B is in communication with the swash plate chamber 33. As described above, the first suction chamber 27A is in communication with the swash plate chamber 33 through the first communication passage 37A. Therefore, the second suction chamber 27B is in communication with the first suction chamber 27A and the inlet port 170 through the first and second communication passages 37A, 37B and the swash plate chamber 33. The length of the first communication passage 37A is the same as that of the second communication passage 37B. The inner diameter of the first communication passage 37A is the same as that of the second communication passage 37B.

The second cylinder block 23 has therein a second retainer groove 23E that is recessed in the second cylinder block 23 and adjustably determines the deflection of the second suction reed valve 411A which will be described later. That is, the second retainer groove 23E is provided in the second accommodation chamber forming part. The shape and depth of the first retainer groove 21E formed in the first cylinder block 21 are the same as those of the second retainer groove 23E formed in the second cylinder block 23.

A first valve forming plate 39 is provided between the rear housing 17 and the first cylinder block 21. A second valve forming plate 41 is provided between the front housing 19 and the second cylinder block 23.

The first valve forming plate 39 includes a first valve plate 390, a first suction valve plate 391, a first discharge valve plate 392 and a first retainer plate 393. A first suction hole 390A is formed through the first valve plate 390, the first discharge valve plate 392 and the first retainer plate 393 for each first cylinder bore 21A. A first discharge hole 390B is formed through the first valve plate 390 and the first suction valve plate 391 for each first cylinder bore 21A. A first communication hole 390C is formed through the first valve plate 390, the first suction valve plate 391, the first discharge valve plate 392 and the first retainer plate 393.

Each first cylinder bore 21A is communicable with the first suction chamber 27A through the first suction hole 390A. Each first cylinder bore 21A is communicable with the first discharge chamber 29A through the first discharge hole 390B. The first suction chamber 27A is in communication with the first communication passage 37A through the first communication hole 390C.

The first suction valve plate 391 is provided on the front surface of the first valve plate 390. The first suction valve plate 391 has a plurality of first suction reed valves 391A that open and close the respective first suction holes 390A by elastic deformation. The first discharge valve plate 392 is provided on the rear surface of the first valve plate 390. The first discharge valve plate 392 has a plurality of first discharge reed valves 392A that open and close the respective first discharge holes 390B by elastic deformation. The first retainer plate 393 is provided on the rear surface of the first discharge valve plate 392 and regulates the lift of the first discharge reed valves 392A.

The second valve forming plate 41 includes a second valve plate 410, a second suction valve plate 411, a second discharge valve plate 412 and a second retainer plate 413. A second suction hole 410A is formed through the second valve plate 410, the second discharge valve plate 412 and the second retainer plate 413 for each second cylinder bore 23A. A second discharge hole 410B is formed through the second valve plate 410 and the second suction valve plate 411 for each second cylinder bore 23A. A second communication hole 410C is formed through the second valve plate 410, the second suction valve plate 411, the second discharge valve plate 412 and the second retainer plate 413.

Each second cylinder bore 23A is communicable with the second suction chamber 27B through the second suction hole 410A. Each second cylinder bore 23A is communicable with the second discharge chamber 29B through the second discharge hole 410B. The second suction chamber 27B is in communication with the second communication passage 37B through the second communication hole 410C.

The second suction valve plate 411 is provided on the rear surface of the second valve plate 410. The second suction valve plate 411 has a plurality of second suction reed valves 411A that open and close the respective second suction holes 410A by elastic deformation. The second discharge valve plate 412 is provided on the front surface of the second valve plate 410. The second discharge valve plate 412 has a plurality of second discharge reed valves 412A that open and close the respective second discharge holes 410B by elastic deformation. The second retainer plate 413 is provided on the front surface of the second discharge valve plate 412 and regulates the lift of the second discharge reed valves 412A.

The first suction hole 390A and the second suction hole 410A are formed to have the same opening area. Similarly, the first discharge hole 390B and the second discharge hole 410B are formed to have the same opening area. Similarly, the first communication hole 390C and the second communication hole 410C are formed to have the same opening area.

The first suction valve plate 391 and the second suction valve plate 411 are formed to have the same thickness. Therefore, the thickness of the first suction reed valve 391A is the same as that of the second suction reed valve 411A. The first discharge valve plate 392 and the second discharge valve plate 412 are formed to have the same thickness. Therefore, the thickness of the first discharge reed valve 392A is also the same as that of the second discharge reed valve 412A. In the compressor according to the present embodiment, the first retainer plate 393 and the second retainer plate 413 are formed symmetrically so that the lift of the first discharge reed valve 392A determined by the first retainer plate 393 is the same as that of the second discharge reed valve 412A determined by the second retainer plate 413.

As described above, each first cylinder bore 21A is communicable with the first suction chamber 27A through the corresponding first suction hole 390A. The first suction chamber 27A is in communication with the inlet port 170 through the first suction passage 171. Thus, the first suction passage 171, the first suction chamber 27A and the corresponding first suction hole 390A cooperate to form a first suction flow passage 2.

The second suction chamber 27B is in communication with the inlet port 170 through the first and second communication passages 37A, 37B, the swash plate chamber 33, the first suction chamber 27A and the first suction passage 171. Thus, the first suction passage 171, the first suction chamber 27A, the swash plate chamber 33, the first and second communication holes 390C, 410C, the first and second communication passages 37A, 37B, the second suction chamber 27B and the second suction hole 410A cooperate to form a second suction flow passage 4.

The first and second suction chambers 27A and 27B are in communication with the swash plate chamber 33 through the first and second communication passages 37A, 37B and the first and second communication holes 390C, 410C, so that the pressure in the first and second suction chambers 27A and 27B is substantially the same as that in the swash plate chamber 33. The pressures in the swash plate chamber 33 and in the first and second suction chambers 27A and 27B are lower than those in the first and second discharge chambers 29A, 29B because refrigerant gas flowed through an evaporator is flowed into the swash plate chamber 33 through the inlet port 170, the first suction passage 171, the first suction chamber 27A and the first communication passage 37A.

The drive shaft 3 includes a shaft body 30 and first and second support members 43A, 43B. The shaft body 30 extends rearward from the boss 19A and is inserted through the first and second slide bearings 22A, 22B. Thus, the shaft body 30 and hence the drive shaft 3 is supported rotatably around the axis of rotation O. The front and rear ends of the shaft body 30 are located in the boss 19A and in the pressure control chamber 25, respectively.

The swash plate 5 and the actuator 13 are mounted on the shaft body 30 and arranged in the swash plate chamber 33.

The first support member 43A is press-fitted on the shaft body 30 adjacent to the front end of the shaft body 30 to be in sliding contact with the second slide bearing 22B. The first support member 43A is formed with a flange 431 that is in contact with the second thrust bearing 35B and a mounting portion (not shown) in which a second pin 47B described later is inserted. A first return spring 44A is fixed at the front end thereof to the first support member 43A. The first return spring 44A extends in the direction of the axis of rotation O from the first support member 43A toward the swash plate chamber 33.

The second support member 43B is press-fitted on the shaft body 30 at a position adjacent to the rear end of the shaft body 30 so as to be in sliding contact with the first slide bearing 22A. The second support member 43B is formed with a flange 432 that is located in the first accommodating chamber 21C between the first thrust bearing 35A and the actuator 13.

The shaft body 30 has therein an axial passage 3B extending in the direction of the axis of rotation O from the rear end toward the front end of the shaft body 30 and a radial passage 3C that extends radially outward from the front end of the axial passage 3B and opens at the outer periphery of the shaft body 30. The rear end of the axial passage 3B is opened to the pressure control chamber 25 and the radially outer end of the radial passage 3C is opened to a pressure control chamber 13C described later.

The drive shaft 3 has a threaded front end 3D and is connected to a pulley or an electromagnetic clutch (not shown in the drawing) through this threaded front end 3D. A belt (not shown in the drawing) driven by an engine is wound around the pulley or the pulley of the electromagnetic clutch.

The swash plate 5 is of an annular plate shape and has a rear surface 5A and a front surface 5B. In the swash plate chamber 33, the rear surface 5A faces the first cylinder bore 21A or faces rearward. The rear surface 5A side of the swash plate 5 corresponds to one side of the swash plate of the present invention. The front surface 5B faces the second cylinder bore 23A or faces frontward. The front surface 5B side of the swash plate 5 corresponds to the other side of the swash plate of the present invention.

The swash plate 5 is fixed on a ring plate 45 which is of an annular plate shape and has at the center thereof a hole 45A. The swash plate 5 is mounted on the drive shaft 3 in the swash plate chamber 33 with the shaft body 30 of the drive shaft 3 inserted through the hole 45A.

The aforementioned link mechanism 7 has a lug arm 49. The lug arm 49 is disposed in the swash plate chamber 33 frontward of the swash plate 5 and located between the swash plate 5 and the first support member 43. The lug arm 49 is formed to have a substantially L shape shown in FIG. 1. When the inclination angle of the swash plate 5 becomes minimum with respect to the direction perpendicular to the axis of rotation O, the lug arm 49 is in contact with the flange 431 of the first support member 43A. Thus, the lug arm 49 keeps the swash plate 5 at its minimum inclination angle. The lug arm 49 has in the rear end thereof a weight member 49A that extends over an approximate semicircle in the peripheral direction of the actuator 13. The shape of the weight member 49A may be changed.

As shown in FIG. 1, the rear end of the lug arm 49 is connected to one end of the ring plate 45 by a first pin 47A so that the lug arm 49 is pivotally supported at the rear end thereof by one end of the ring plate 45 of the swash plate 5 and swingable around a first axis M1 that corresponds to the axis of the first pin 47A. The first axis M1 extends in the direction perpendicular to the axis of rotation O of the drive shaft 3.

The front end of the lug arm 49 is connected to the first support member 43A by the second pin 47B so that the lug arm 49 is pivotally supported at the front end thereof by the first support member 43A of the drive shaft 3 and swingable around a second axis M2 that corresponds to the axis of the second pin 47B. The second axis M2 extends parallel to the first axis M1. The lug arm 49 and the first and second pins 47A, 47B correspond to the link mechanism of the present invention.

The weight member 49A is provided extending on the rear side of the first axis M1 opposite from the second axis M2. Thus, the lug arm 49 is supported by the ring plate 45 through the first pin 47A. As a result, the weight member 49A is inserted in a groove 45B of the ring plate 45 and disposed in the rear surface of the ring plate 45, namely in the rear surface 5A side of the swash plate 5. Centrifugal force developed during rotation of the swash plate 5 around the axis of rotation O acts on the weight member 49A in the rear surface 5A side of the swash plate 5.

The swash plate 5 is connected to the drive shaft 3 by the link mechanism 7, so that the swash plate 5 and the drive shaft 3 rotate together. The link mechanism 7 is so arranged that the swash plate 5 is placed at a position adjacent to the second cylinder bore 23A when the inclination angle of the swash plate 5 becomes minimum. The front part and the rear end of the lug arm 49 are swung around the first axis M1 and the second axis M2, respectively and the swash plate 5 changes the inclination angle thereof, accordingly.

Each piston 9 has a first head 9A at the rear end thereof, a second head 9B at the front end thereof and a recessed part 9C at the center thereof. The first head 9A is received in the first cylinder bore 21A so as to slide therein reciprocally. A first compression chamber 21D is formed in each first cylinder bore 21A by the first head 9A and the first valve forming plate 39. The second head 9B is received in the second cylinder bore 23A so as to slide therein reciprocally. A second compression chamber 23D is formed in each second cylinder bore 23A by the second head 9B and the second valve forming plate 41.

As described above, the inner diameter of the first cylinder bore 21A is smaller than that of the second cylinder bore 23A, so that the outer diameter of the first head 9A is smaller than that of the second head 9B. The first cylinder bore 21A and the second cylinder bore 23A are formed coaxially, so that the first head 9A and the second head 9B are also disposed coaxially.

The length of the first head 9A in the stroke direction of the piston 9 is the same as that of the second head 9B, so that the length from the center of the recessed part 9C of each piston 9 to the top of the first head 9A is the same as that of the second head 98.

A pair of hemispherical shoes 11A, 11B is provided in the recessed part 9C of each piston 9 in such a manner that the rotation of the swash plate 5 is converted to reciprocating movement of the piston 9 in its associated first and second cylinder bores 21A, 23A. The shoes 11A, 11B correspond to the conversion mechanism of the present invention. Thus, the first and second heads 9A, 9B can reciprocate in the first and second cylinder bores 21A, 23A, respectively, with the stroke length that is determined according to the inclination angle of the swash plate 5.

As described above, when the inclination angle of the swash plate 5 becomes minimum, the swash plate 5 is located in the swash plate chamber 33 closer to the second cylinder bore 23A than to the first cylinder bore 21A. When the inclination angle of the swash plate 5 becomes maximum, as shown in FIG. 1, and the stroke length of the piston 9 becomes maximum, accordingly, the top dead center position of the first head 9A is closest to the first valve forming plate 39 and the top dead center position of the second head 9B is closest to the second valve forming plate 41. On the other hand, when the inclination angle of the swash plate 5 becomes minimum, as shown in FIG. 3 and the stroke length of the piston 9 decreases to minimum, the top dead center position of the first head 9A is located farthest from the first valve forming plate 39. Then, the top dead center position of the second head 9B is similar to the position when the stroke length of the piston 9 is maximum and keeps located at a position close to the second valve forming plate 41.

As shown in FIG. 1, the actuator 13 is disposed in the swash plate chamber 33 at a position adjacent to the first cylinder bore 21A. The actuator 13 is movable in such a way that a part of the actuator 13 enters the first accommodating chamber 21C and is accommodated in the first accommodating chamber 21C.

The actuator 13 has a movable member 13A, a fixed member 13B and a pressure control chamber 13C. The actuator body of the present invention is formed by the movable member 13A and the fixed member 13B. The pressure control chamber 13C is formed between the movable member 13A and the fixed member 13B.

The movable member 13A has a body portion 130 and a peripheral wall 131. The body portion 130 is formed in the rear part of the movable member 13A and extends radially from the axis of rotation O. The peripheral wall 131 extends frontward from the outer periphery of the body portion 130. The peripheral wall 131 has at the front end thereof a connecting part 132. The movable member 13A is formed by the body portion 130, the peripheral wall 131 and the connecting part 132 and has a bottomed cylindrical shape.

The fixed member 13B is formed in a disk shape having an inner diameter that is substantially the same as that of the movable member 13A. A second return spring 44B is provided between the fixed member 138 and the ring plate 45. Specifically, the second return spring 44B is fixed at the rear end thereof to the fixed member 13B and at the front end thereof to the other end side of the ring plate 45.

The shaft body 30 is inserted through the movable member 13A and the fixed member 13B, so that the movable member 13A positioned in the first accommodating chamber 21C is disposed on the opposite side of the swash plate 5 from the link mechanism 7. On the other hand, the fixed member 138 is disposed rearward of the swash plate 5 and in the movable member 13A and surrounded by the peripheral wall 131. The pressure control chamber 13C is formed between the movable member 13A and the fixed member 13B. The pressure control chamber 13C is separated from the swash plate chamber 33 by the body portion 130 and the peripheral wall 131 of the movable member 13A and the fixed member 13B. As described above, the radial passage 3C is opened to the pressure control chamber 13C. The pressure control chamber 13C is in communication with the pressure control chamber 25 through the radial passage 3C and the axial passage 3B.

The movable member 13A is mounted on the shaft body 30 such that the movable member 13A is rotatable together with the drive shaft 3 and slidable in the direction of the axis of rotation O of the drive shaft 3. On the other hand, the fixed member 13B is fixedly mounted on the shaft body 30 for rotation therewith, but immovable in the axial direction of the drive shaft 3. Therefore, the movable member 13A slides axially relative to the fixed member 13B in moving in the axial direction of the drive shaft 3.

The other end of the ring plate 45 is connected to the connecting part 132 of the movable member 13A by a third pin 47C, so that the other end of the ring plate 45 and hence the swash plate 5 is supported swingably around the axis M3 that is the axis of the third pin 47C by the movable member 13A. The axis M3 extends parallel to the first and second axes M1, M2. Thus, the movable member 13A is connected to the swash plate 5. When the inclination angle of the swash plate 5 becomes maximum, the movable member 13A is brought into contact with the flange 432.

Referring to FIG. 2, the control mechanism 15 has a bleed passage 15A, a supply passage 15B, a control valve 15C and an orifice 15D.

The bleed passage 15A is connected at one end thereof to the pressure control chamber 25 and at the other end thereof to the first suction chamber 27A, so that the pressure control chamber 13C, the pressure control chamber 25 and the first suction chamber 27A are in communication with each other through the bleed passage 15A, the axial passage 3B and the radial passage 3C. The supply passage 15B is connected at one end thereof to the pressure control chamber 25 and at the other end thereof to the first discharge chamber 29A. The pressure control chamber 13C, the pressure control chamber 25 and the first discharge chamber 29A are in communication with each other through the supply passage 15B, the axial passage 3B and the radial passage 3C. The orifice 15D is provided in the supply passage 15B and regulates the flow rate of the refrigerant gas flowing through the supply passage 15B.

The control valve 15C is provided in the bleed passage 15A for controlling the opening of the bleed passage 15A and hence the flow rate of the refrigerant gas flowing through the bleed passage 15A according to the pressure in the first suction chamber 27A.

The inlet port 170 of the compressor in FIG. 1 is connected through a tube to an evaporator (not shown) of the refrigerant gas circuit and the aforementioned outlet port (not shown in the drawing) is connected through a tube to a condenser (not shown) of the refrigerant gas circuit. The condenser is connected to the evaporator through tubes and an expansion valve. The refrigerant gas circuit is composed of the compressor, the evaporator, the expansion valve, the condenser and the like. Illustration of the evaporator, the expansion valve, the condenser and tubes is omitted.

In the compressor according to the arrangement described above, the drive shaft 3 rotates the swash plate 5, which causes the pistons 9 to reciprocate in the first and second cylinder bores 21A, 23A. The volumes of the first and second compression chambers 21D, 23D and hence the displacement or the capacity of the compressor changes according to the stroke length of the pistons 9. In the compressor, the suction process in which refrigerant gas is drawn into the first and second compression chambers 21D, 23D, the compression process in which the refrigerant gas is compressed in the first and second compression chambers 21D, 23D and the discharge process in which the compressed refrigerant gas is discharged from the first and second compression chambers 21D, 23D are repeated in this order.

In the suction process of any first cylinder bore 21A, the first suction reed valve 391A opens the first suction hole 390A by the pressure difference created between the first compression chamber 21D and the first suction chamber 27A, so that refrigerant gas in the first suction chamber 27A is drawn into the first compression chamber 21D. Similarly, in the suction process of any second cylinder bore 23A, the second suction reed valve 411A opens the second suction hole 410A by the pressure difference between the second compression chamber 23D and the second suction chamber 27B, so that refrigerant gas in the second suction chamber 27B is flowed into the second compression chamber 23D.

In the discharge process, the first discharge reed valve 392A opens the first discharge hole 390B by the pressure difference between the first compression chamber 21D and the first discharge chamber 29A, so that the refrigerant gas compressed in the first compression chamber 21D is discharged out into the first discharge chamber 29A. Similarly, the second discharge reed valve 412A opens the second discharge hole 410B by the pressure difference between the second compression chamber 23D and the second discharge chamber 29B, so that refrigerant gas compressed in the second compression chamber 23D is discharged out into the second discharge chamber 29B.

In the suction process of any cylinder bore, piston compression reaction force acts on the rotating parts including the swash plate 5, the ring plate 45, the lug arm 49 and the first pin 47A in the direction that reduces the inclination angle of the swash plate 5. Changing the inclination angle of the swash plate 5 changes the stroke length of the piston 9 and hence performs the displacement control.

Specifically, in the control mechanism 15 of FIG. 2, when the control valve 15C increases the flow rate of refrigerant gas flowing through the bleed passage 15A, the refrigerant gas in the first discharge chamber 29A tends to flow less through the supply passage 15B and the orifice 15D and to be stored less in the pressure control chamber 25, accordingly. Thus, the pressure in the pressure control chamber 13C becomes substantially the same as the pressure in the first suction chamber 27A. Therefore, the actuator 13 is moved by piston compression reaction force acting on the swash plate 5, so that the movable member 13A is moved toward the swash plate 5 and to a position close to the lug arm 49, as shown in FIG. 3.

As a result, the other end of the ring plate 45, that is, the other end of the swash plate 5 is swung clockwise around the first axis M3 as seen in FIG. 3 while overcoming the urging force of the second return spring 44B. The rear end of the lug arm 49 is swung counterclockwise around the first axis M1, while the front part of the lug arm 49 swings counterclockwise around the second axis M2, so that the lug arm 49 approaches the flange 431 of the first support member 43A. The swash plate 5 swings with the axis M3 as the point of load, around the first axis M1 as the fulcrum point and the inclination angle of the swash plate 5 approaches zero with respect to the direction perpendicular to the axis of rotation O of the drive shaft 3, so that the stroke length of the piston 9 decreases. Therefore, the volumes of refrigerant gas to be drawn and delivered per revolution of the compressor decrease. The inclination angle of the swash plate 5 shown in FIG. 3 is the minimum inclination angle in the compressor according to the present embodiment.

Centrifugal force developed by the weight member 49A is also applied to the swash plate 5 in such a way that tends to cause the swash plate 5 to incline so as to decrease its inclination angle. The aforementioned movement of the movable member 13A toward the swash plate chamber 33 causes the front end of the movable member 13A to be located inside the weight member 49A. When the inclination angle of the swash plate 5 decreases, approximately half of the movable member 13A on the front side thereof is covered by the weight member 49A.

When the inclination angle of swash plate 5 is decreased, the ring plate 45 is brought into contact with the rear end of the first return spring 44A. As a result, the first return spring 44A is elastically deformed by being compressed by the ring plate 45.

As described above, when the inclination angle of the swash plate 5 decreases and the stroke length of the piston 9 decreases, the top dead center position of the first head 9A is located farther from the first valve forming plate 39. When the inclination angle of the swash plate 5 approaches zero, compression of refrigerant gas is performed slightly in the second compression chamber 23D, while no compression of refrigerant gas is performed in the first compression chamber 21D.

On the other hand, when the control valve 15C shown in FIG. 2 reduces flow rate of the refrigerant gas flowing through the bleed passage 15A, the refrigerant gas in the first discharge chamber 29A tends to flow easily through the supply passage 15B and the orifice 15D and stored in the pressure control chamber 25. Then, the pressure of the pressure control chamber 13C becomes substantially the same as that of the first discharge chamber 29A. As a result, the actuator 13 is moved against piston compression reaction force acting on the swash plate 5, so that the movable member 13A is moved rearward of the swash plate chamber 33, that is, toward the inside of the first accommodating chamber 21C and is located far from the lug arm 49 as shown in FIG. 1.

Therefore, the movable member 13A pulls the other end side of the swash plate 5 rearward at the axis M3 through the connecting part 132, thus causing the other end side of the swash plate 5 to swing counterclockwise around the axis M3. Then, the rear end of the lug arm 49 is swung clockwise around the first axis M1, while the front part of the lug arm 49 is swung clockwise around the second axis M2. The lug arm 49 is then moved away from the flange 431 of the first support member 43A. Thus, the swash plate 5 is swung around the first axis M1 with the axis M3 as the point of load in the direction that increases the inclination angle of the swash plate 5, with the result that the stroke length of the piston 9 is increased and the suction capacity and the displacement per revolution increase. The inclination angle of the swash plate 5 shown in FIG. 1 is the maximum inclination angle in the compressor according to the present embodiment.

In the compressor, the inner diameter of the first cylinder bore 21A is smaller than that of the second cylinder bore 23A, so that the outer diameter of the second head 9B is larger than that of the first head 9A. For example, it may be contemplated that the first suction flow passage 2 and the second suction flow passage 4 have the same structure so that refrigerant gas drawn in the inlet port 170 is flowed for substantially the same distance into each of the first compression chambers 21D and each of the second compression chamber 23D.

In this case, the amplitude of the intake pulsation occurring in the first compression chamber 21D which is indicated by dashed-dotted line in FIG. 4 is smaller than that in the second compression chamber 23D which is indicated by dashed line in FIG. 4. The intake pulsation that remains in such compressor results from combining the above intake pulsations and is indicated by solid line in FIG. 4.

In the compressor according to the first embodiment, however, the first suction flow passage 2 and the second suction flow passage 4 have different structures. In suction process of any first cylinder bore 21A, refrigerant gas is directly supplied from the inlet port 170 into the first suction chamber 27A through the first suction passage 171. As described above, the first suction reed valve 391A is bent and opens the first suction hole 390A thereby to allow the refrigerant gas drawn from the inlet port 170 into the first suction chamber 27A to be introduced into the first compression chamber 21D. In the second suction flow passage 4 during the suction process of a second cylinder bore 23A, on the other hand, refrigerant gas is flowed through the inlet port 170, the first suction passage 171, the first suction chamber 27A, the first communication passage 37A, the swash plate chamber 33 and the second communication passage 37B and into the second suction chamber 27B. Then, the second suction reed valve 411A is bent and opens the second suction hole 410A thereby to allow the refrigerant gas in the second suction chamber 27B to be introduced into the second compression chamber 23D.

Therefore, in the compressor, the intake resistance acting on the refrigerant gas drawn into the first compression chamber 21D in suction process (hereinafter referred to as “the first intake resistance”) is smaller than the intake resistance acting on the refrigerant gas drawn into the second compression chamber 23D in suction process (hereinafter referred to as “the second intake resistance”), so that in the first suction flow passage 2 in which the first intake resistance is small, refrigerant gas is flowed easily into the first compression chamber 21D and the amplitude of intake pulsation occurring in the first compression chamber 21D becomes large. In the second suction flow passage 4 in which the second intake resistance is large, on the other hand, refrigerant gas is flowed less easily into the second compression chamber 23D and the amplitude of the intake pulsation occurring in the second compression chamber 23D is small.

Specifically, as shown in FIG. 5, the amplitude of the intake pulsation occurring in the second compression chamber 23D, which is indicated by dotted line in FIG. 5, is lower due to the relatively large second intake resistance as compared to the case of FIG. 4. On the other hand, the amplitude of the intake pulsation in first compression chamber 21D, which is indicated by dashed-dotted line in FIG. 5, is higher as compared to the case of FIG. 4. In the compressor in which the inner diameter of the first cylinder bores 21A is smaller than that of the second cylinder bores 23A, the difference of the amplitude of the intake pulsation between the first compression chamber 21D and the second compression chamber 23D occurs. However, the difference of the intake pulsation amplitude can be suitably reduced. That is, the intake pulsation combined by the intake pulsation in the first compression chamber 21D and the intake pulsation in the second compression chamber 23D can be reduced as shown in FIG. 5 with a solid line in the compressor. As a result, the intake pulsation is reduced over the entire range of displacements of the compressor and noise can be reduced.

Thus, the compressor according to the first embodiment is advantageous in terms of silence in operation.

In the compressor, the movable member 13A moves frontward in the swash plate chamber 33 to a position close to the fixed member 13B as shown in FIG. 3 thereby to reduce the volume of the pressure control chamber 13C. The swash plate 5 reduces its inclination angle with a decrease of the volume of the pressure control chamber 13C. Allowing the movable member 13A to move frontward in the swash plate chamber 33, the first accommodating chamber 21C also serves as part of the swash plate chamber 33. On the other hand, the movable member 13A moves rearward in the swash plate chamber 33 away from the fixed member 138 to a position shown in FIG. 1 thereby to increase the volume of the pressure control chamber 13C. The swash plate 5 increases its inclination angle with an increase of the volume of the pressure control chamber 13C.

That is, with an increase in the volume of the pressure control chamber 13C, the inclination angle of the swash plate 5 becomes larger, while the volume of the swash plate chamber 33 gradually becomes smaller. As shown in FIG. 1, when the inclination angle of the swash plate 5 becomes maximum, the volume of the swash plate chamber 33 becomes minimum. Therefore, the muffler effect of the swash plate chamber 33 is suppressed with an increasing inclination angle of the swash plate 5 and the reduction effect of the intake pulsation in the second compression chamber 23D is suppressed. That is, the intake pulsation amplitude in the second compression chamber 23D may be increased to a level that is close to that in the first compression chamber 21D. Thus, the difference of the intake pulsation between the first compression chamber 21D and the second compression chamber 23D can be suitably reduced according a change of the displacement of the compressor.

Second Embodiment

In the compressor according to the second embodiment shown in FIG. 6, no inlet port and no first suction passage such as 170 and 171 of the first embodiment shown in FIGS. 1 and 3 is formed in the rear housing 17, so that the first suction chamber 27A is smaller than that of the first embodiment.

The first cylinder block 21 of the compressor according to the second embodiment has therein a first communication passage 38A and an inlet port 330. The second cylinder block 23 of the compressor according to the second embodiment has therein a second communication passage 38B. The inner diameter of the first communication passage 38A is the same as that of the second communication passage 38B.

As in the case of the compressor according to the first embodiment, the first communication passage 38A is communication with the swash plate chamber 33. The first suction chamber 27A is in communication with the first communication passage 38A through the first communication hole 390C. Thus, the inlet port 330 is in communication with the first suction chamber 27A through the first communication passage 38A.

As in the case of the compressor according to the first embodiment, the second communication passage 38B is in communication with the swash plate chamber 33. The second suction chamber 27B is in communication with the second communication passage 38B through the second communication hole 410C. Thus, the inlet port 330 is in communication with the second suction chamber 27B through the second communication passage 38B.

The inlet port 330 is formed through the first cylinder block 21 at a position that is adjacent to the front end of the first cylinder block 21 and located approximately at the longitudinal center of the housing 1. The swash plate chamber 33 is connected through the inlet port 330 to an evaporator (not shown in the drawing) forming a part of the refrigerant gas circuit in which the present compressor is connected. Because the inlet port 330 is located approximately at the longitudinal center of the housing 1, the distance from the first communication passage 38A to the inlet port 330 is substantially the same as that from the second communication passage 38B to the inlet port 330.

As shown in FIG. 7, the first suction valve plate 391 is thinner than the second suction valve plate 411, so that the first suction reed valve 391A is thinner than the second suction reed valve 411A. The first suction hole 390A, the second suction hole 410A, the first discharge holes 390B and the second discharge holes 410B are formed substantially in the same size, or the opening as those of the compressor according to the first embodiment. The first retainer plate 393 and the second retainer plate 413 are formed to have substantially the same shape as those of the compressor according to the first embodiment.

In the suction process of any first cylinder bore 21A of the compressor, refrigerant gas drawn from an evaporator into the swash plate chamber 33 through the inlet port 330 is flowed through the first communication passage 38A into the first suction chamber 27A and introduced through the first suction hole 390A into the first compression chamber 21D. The first suction flow passage 2A is formed by the first communication passage 38A, the first suction chamber 27A and each of the first suction hole 390A.

In the suction process of any second cylinder bore 23A, refrigerant gas drawn from the evaporator through the inlet port 330 into the swash plate chamber 33 is flowed through the second communication passage 38B into the second suction chamber 27B and introduced thorough the second suction holes 410A into the second compression chamber 23D. The second suction flow passage 4A is formed by the second communication passage 38B, the second suction chamber 27B and each of the second suction holes 410A. In the description of the compressor according to the second embodiment, the same reference numerals are used to denote components that are similar to their counterparts of the first embodiment and the description thereof will be omitted.

In the compressor of FIG. 6, the first suction reed valves 391A is thinner than the second suction reed valves 411A, so that in suction process, the first suction reed valve 391A opens the first suction hole 390A more easily than the second suction reed valve 411A opens the second suction hole 410A. The first intake resistance is smaller than the second intake resistance and, therefore, in the suction process, refrigerant gas can be drawn into the first compression chamber 21D more easily than refrigerant gas drawn into the second compression chamber 23D. That is, as shown in FIG. 5, the increased second intake resistance reduces the amplitude of the intake pulsation in the second compression chamber 23D with a dashed line compared to the case shown in FIG. 4. On the other hand, the decreased first suction resistance increases the amplitude of the intake pulsation in the first compression chamber 21D shown in FIG. 5 with a dashed-dotted line compared to the case shown in FIG. 4

Because the inner diameter of the first cylinder bore 21A is smaller than that of the second cylinder bore 23A, the difference of the intake pulsation between the first compression chamber 21D and the second compression chamber 23D can be suitably reduced. The other effects of the compressor according to the second embodiment are the same as those of the compressor according to the first embodiment.

Third Embodiment

Referring to FIG. 8, the compressor according to the third embodiment differs from the compressor of the second embodiment in that the first suction hole 390A of the first valve forming plate 39 and the second suction hole 410A of the second valve forming plate 41 are formed to have the different size with respect to the opening area thereof. Specifically, the inner diameter of the first suction hole 390A is larger than that of the second suction hole 410A.

The compressor according to the third embodiment differs from the compressor of the second embodiment also in that the first suction valve plate 391 and the second suction valve plate 411 are formed to have the same thickness as in the case of the compressor according to the first embodiment. Therefore, the thickness of the first suction reed valve 391A is the same as that of the second suction reed valve 411A. The rest of the structure of the compressor according to the third embodiment, including the opening areas of the first discharge hole 390B and the second discharge hole 410B, is substantially the same as the compressor according to the second embodiment.

In the compressor according to the third embodiment, refrigerant gas drawn from an evaporator into the swash plate chamber 33 through the inlet port 330 is flowed through the first and second suction flow passages 2A, 4A into the first and second compression chamber 21D, 23D, respectively in a manner similar to the case of the compressor according to the second embodiment.

As indicated above, the first suction hole 390A provides a larger opening than the second suction hole 410A, so that refrigerant gas flows through first suction hole 390A more easily than through the second suction hole 410A. Therefore, the first intake resistance is smaller than the second intake resistance. In suction process of any first cylinder bore 21A, refrigerant gas is flowed into the first compression chamber 21D more easily than in the second compression chamber 23D. The inner diameter of the first cylinder bores 21A is smaller than that of the second cylinder bores 23A, so that the difference of the intake pulsation between the first compression chamber 21D and the second compression chamber 23D can be suitably reduced. The other effects of the compressor according to the third embodiment are the same as those of the compressor according to the first embodiment.

Fourth Embodiment

The compressor according to the fourth embodiment shown in FIG. 9 differs from the compressor of the second embodiment in that the first retainer groove 21E and the second retainer groove 23E are formed differently. Specifically, the first retainer groove 21E is formed deeper than the second retainer groove 23E.

The compressor according to the fourth embodiment also differs from the compressor of the second embodiment also in that the thicknesses of the first suction reed valve 391A and the second suction reed valve 411A are the same. The rest of the compressor according to the fourth embodiment including the opening area of the first discharge hole 390B and the second discharge hole 410B is substantially the same as the compressor according to the second embodiment.

As in the compressors of the second and third embodiments, refrigerant gas drawn from an evaporator into the swash plate chamber 33 through the inlet port 330 is introduced through the first and second suction flow passages 2A, 4A into the first and second compression chamber 21D, 23D, respectively.

In the compressor according to the fourth embodiment wherein the first retainer groove 21E is deeper than the second retainer groove 23E, the first suction reed valve 391A is bent larger than the second suction reed valve 411A during suction process.

Thus, the first suction reed valve 391A opens larger than the second suction reed valve 411A during suction process, so that refrigerant gas through the first suction hole 390A is flowed more easily than through the second suction hole 410A. Therefore, the first intake resistance is also smaller than the second intake resistance, so that refrigerant gas is flowed more easily into the first compression chamber 21D than through the second compression chamber 23D during suction process. Thus, the inner diameter of the first cylinder bores 21A is smaller than that of the second cylinder bores 23A, so that the difference of the amplitude of the intake pulsation between the first compression chamber 21D and the second compression chamber 23D can be suitably reduced. The other effects of the compressor according to the fourth embodiment are the same as those of the compressor according to the first embodiment.

Fifth Embodiment

As in the compressor according to the second embodiment, the compressor according to the fifth embodiment shown in FIG. 10 has the first and second communication passages 38A, 38B formed in the first and second cylinder blocks 21, 23, respectively. However, the compressor of FIG. 10 differs from the compressor of the second embodiment in that the first and second communication passages 38A, 38B have different inner diameters. Specifically, the inner diameter of the first communication passage 38A is larger than that of the second communication passage 38B and, therefore, the diameter of the first communication hole 390C of the first valve forming plate 39 is larger than that of the second communication hole 410C of the second valve forming plate 41.

The thickness of the first suction reed valves 391A is substantially the same as that of the second suction reed valves 411A as in the case of the compressor according to the first embodiment. The rest of structure of the compressor according to the fifth embodiment, including the opening area of the first discharge hole 390B and the second discharge hole 410B, is substantially the same as that of the compressor according to the second embodiment.

As in the case of the compressors according to the second, third and forth embodiments, refrigerant gas drawn from an evaporator through the inlet port 330 into the swash plate chamber 33 is flowed through the first and second suction flow passages 2A, 4A into the first and second compression chamber 21D, 23D, respectively. Because, the inner diameter of the first communication passage 38A is larger than that of the second communication passage 38B, the inner diameter of the first suction flow passage 2A is larger than that of the second suction flow passage 4A.

During the suction process of any cylinder bore, refrigerant gas in the swash plate chamber 33 flows more easily through the first suction flow passage 2A than through the second suction flow passage 4A. Therefore, the first intake resistance is smaller than the second intake resistance, so that refrigerant gas is flowed more easily into the first compression chamber 21D than into the second compression chamber 23D during the suction process. Because, the inner diameter of the first cylinder bore 21A is smaller than that of the second cylinder bore 23A, the difference of the amplitude of the intake pulsation between the first compression chamber 21D and the second compression chamber 23D can be suitably reduced. The other effects of the compressor according to the fourth embodiment are the same as those of the compressor according to the first embodiment.

Sixth Embodiment

As in the case of the compressor according to the second embodiment, the compressor according to the sixth embodiment shown in FIG. 11 has the first communication passage 38A and the inlet port 330 formed in the first cylinder block 21 and the second communication passage 38B formed in the second cylinder block 23. However, the compressor of the present sixth embodiment differs from the compressor of the second embodiment in that the inlet port 330 is formed through the first cylinder block 21 at a position adjacent to the center of the first cylinder block 21. That is, the inlet port 330 is formed at a position that is closer to the rear end of the housing 1 than the inlet port 330 of the second embodiment, so that the distance between the first communication passage 38A and the inlet port 330 is different from that between the second communication passage 38B and the inlet port 330. Specifically, the distance between the first communication passage 38A and the inlet port 330 is smaller than that between the second communication passage 38B and the inlet port 330.

As in the case of the compressor of the first embodiment, the thickness of the first suction reed valve 391A is the same as that of the second suction reed valve 411A in the compressor according to the sixth embodiment. The rest of the structure of the compressor according to the sixth embodiment, including the opening areas of the first discharge hole 3908 and of the second discharge holes 410B, is substantially the same as that of the compressor according to the second embodiment.

As in the case of the compressors according to the second through fifth embodiments, refrigerant gas flowed from an evaporator through the inlet port 330 into the swash plate chamber 33 is introduced through the first and second suction flow passages 2A, 4A into the first and second compression chamber 21D, 23D, respectively. The distance between the first communication passage 38A and the inlet port 330 is smaller from that between the second communication passage 38B and the inlet port 330. Therefore, the overall length of the first suction flow passage 2A is shorter than that of the second suction flow passage 4A.

During the suction process of any cylinder bore, refrigerant gas drawn through the inlet port 330 is flowed more easily through the first suction flow passages 2A than through the second suction flow passage 4A. Therefore, the first intake resistance is smaller that the second intake resistance, and in the suction process, refrigerant gas is drawn more easily into the first compression chamber 21D than into the second compression chamber 23D. According to the above-described compressor, wherein the inner diameter of the first cylinder bore 21A is smaller than the second cylinder bore 23A, the difference of the amplitude of the intake pulsation between the first compression chamber 21D and the second compression chamber 23D can be suitably reduced. The other effects of the compressor according to the sixth embodiment are the same as that of the compressor according to the first embodiment.

Seventh Embodiment

Referring to FIG. 12, the compressor according to the seventh embodiment has a rear housing 18 instead of the rear housing 17 of the compressor according to the first embodiment. The compressor has a first valve forming plate 51 between the rear housing 18 and the first cylinder block 21. The drive shaft 3 is formed by a shaft body 300, the first support member 43A and a second support member 46.

As in the case of the compressor according to the second embodiment, in the compressor according to the seventh embodiment, the first cylinder block 21 has therethrough the first communication passage 38A and the inlet port 330 and the second cylinder block 23 has formed therethrough the second communication passage 38B.

Like the rear housing 17 in the compressor of the first embodiment, the rear housing 18 has therein the control mechanism 15, the first suction chamber 27A and the first discharge chamber 29A. The rear housing 17 has further therein the pressure control chamber 250. The pressure control chamber 250 is formed smaller than the pressure control chamber 25 in the first embodiment. By forming the pressure control chamber 250 smaller, the first suction chamber 27A in the rear housing 18 may be formed larger. An O ring 251 is provided in the pressure control chamber 250. Though not shown in the drawing, the pressure control chamber 250 is in communication with the first suction chamber 27A and the first discharge chamber 29A through the bleed passage 15A and the supply passage 15B. Unlike the compressor according to the first embodiment, no inlet port 170 and no first suction passage 171 is formed in the rear housing 18.

A first suction passage 21F is formed in the first cylinder block 21, extending from the first shaft hole 21B toward the first cylinder bore 21A. A communication hole 220 is formed in the first slide bearing 22A in communication with the first suction passage 21F. In the compressor of the present embodiment, no first retainer groove such as 21E is formed in the first cylinder block 21.

The first valve forming plate 51 has a first valve plate 510, a first discharge valve plate 511 and a first retainer plate 512. The first valve plate 510 has therein the first discharge hole 5108 for each first cylinder bore 21A. A first communication hole 510C and an insertion hole 510D are formed in the first valve plate 510, the first discharge valve plate 511 and the first retainer plate 512.

The first cylinder bores 21A is communicable with the first discharge chamber 29A through the first discharge hole 5108. The first suction chamber 27A is in communication with the first communication passage 38A through the first communication hole 510C. The rear end of the drive shaft 3 is inserted through the insertion hole 510D. The opening area of the first discharge hole 510B is the same as that of the second discharge hole 410B. The opening area of the first communication hole 510C is the same as that of the second communication hole 410C.

A first discharge valve plate 511 is provided on the rear surface of the first valve plate 510. The first discharge valve plate 511 is formed with a plurality of first discharge reed valves 511A that open and close the respective first discharge holes 510B by elastic deformation. The first retainer plate 512 is provided on the rear surface of the first discharge valve plate 511. The first retainer plate 512 regulates the lift of the first discharge reed valve 511A. The first retainer plate 512 and the second retainer plate 413 are formed symmetrically, so that the lift of the first discharge reed valve 511A is the same as that of the second discharge reed valve 412A.

Unlike the shaft body 30 of the compressor according to the first embodiment, the shaft body 300 is formed so that the outer diameter of the rear end thereof is smallest of the other portions thereof and smaller than the inner diameter of the insertion hole 510D. The rear end of the shaft body 300 is inserted through the insertion hole 510D into the pressure control chamber 250. The O ring 251 is mounted on the rear end of the shaft body 300 for sealing the pressure control chamber 250.

Like the shaft body 30, the shaft body 300 has therein the axial passage 3B and the radial passage 3C. The pressure control chamber 250 is in communication with the pressure control chamber 13C through the axial passage 3B and the radial passage 3C.

The first support member 43A is press-fitted on the front end portion of the shaft body 300 and the second support member 46 is press-fitted on the rear end portion of the shaft body 300. The second support member 46 is in sliding contact with the first slide bearing 22A. The second support member 46 is formed with a flange 460. The flange 460 is formed between the first thrust bearing 35A and the actuator 13 and located in the first accommodating chamber 21C. When the inclination angle of the swash plate 5 becomes maximum, the movable member 13A is brought into contact with the flange 460.

As described above, the diameter of the rear end portion of the shaft body 300 is small, so that a communication passage 38C is formed between the second support member 46 and the shaft body 300. The communication passage 38C is in communication with the first suction chamber 27A through a space between the insertion hole 510D and the rear end portion of the shaft body 300.

A rotating passage 46A is formed in the second support member 46. The rotating passage 46A is in communication with the communication passage 38C and opens on the outer peripheral surface of the second support member 46. The communication passage 38C is brought into communication with the first compression chamber 21D through the first suction passage 21F when the rotating passage 46A is made into communication with the communication hole 220 with the rotation of the drive shaft 3. As a result, the first suction chamber 27A is in communication with the first compression chamber 21D.

The first suction flow passage 2B is formed by the first communication passage 38A, the first suction chamber 27A, the communication passage 38C, the communication hole 220 and the first suction passage 21F. The rest of the structure of the compressor according to the seventh embodiment is substantially the same as the compressor according to the second embodiment.

In the compressor according to the seventh embodiment, refrigerant gas is drawn from the inlet port 330 through the first communication passage 38A into the first suction chamber 27A. The first and second support members 43A, 46 are rotated with the drive shaft 3. Therefore, in suction process of the first compression chamber 21D, the rotating passage 46A is communicable with the communication hole 220. Then, the communication passage 38C is communicable with the first suction passage 21F, so that the refrigerant gas is drawn through the communication passage 38C; the rotating passage 46A, the communication hole 220 and the first suction passage 21F into the first compression chamber 21D. On the other hand, refrigerant gas is drawn through the second suction flow passage 4A into the second compression chamber 23D in the same manner as the compressor according to the second embodiment.

Thus, the communication passage 38C is communicable with the first suction passage 21F during suction process by the rotation of the drive shaft 3 and refrigerant gas in the first suction chamber 27A is drawn into the first compression chamber 21D, so that the first suction resistance is small. As a result, in suction process, refrigerant gas is drawn more easily into the first compression chamber 21D than into the second compression chamber 23D. In the compressor according to the seventh embodiment described above, wherein the inner diameter of the first cylinder bore 21A is smaller than that of the second cylinder bore 23A, the difference of the amplitude of the intake pulsation between the first compression chamber 21D and the second compression chamber 23D can be suitably reduced. The other effects of the compressor according to the seventh embodiment are the same as those of the compressor according to the first embodiment.

Though the present invention has been described with reference to the first through seventh embodiments, the present invention is not limited to such embodiments and it may be modified into alternative embodiments as exemplified below.

It may be so configured that refrigerant gas is drawn through the inlet port 170 or 330 more easily into the first compression chamber 21D than into the corresponding second compression chamber 23D by appropriately combining the features of the compressors according the first through seventh embodiments.

The compressor may have a structure in which the actuator 13 is disposed in the second accommodating chamber 23C and the lug arm 49 is disposed in the first accommodating chamber 21C.

Furthermore, the compressor may have a structure in which the control valve 15C is provide in the supply passage 15B and the orifice 15D in the bleed passage 15A, respectively. In this case, the flow rate of high pressure refrigerant gas flowing through the supply passage 15B can be controlled by the control valve 15C. By so doing, the pressure in the pressure control chamber 13C may be increased rapidly by high pressure in the first discharge chamber 29A, so that the compressor displacement can be rapidly reduced.

The present invention is applicable to an air conditioner and the like. 

What is claimed is:
 1. A swash plate type variable displacement compressor comprising: a housing having therein a suction chamber into which refrigerant gas is drawn through an inlet port, a discharge chamber, a swash plate chamber and a cylinder bore; a drive shaft rotatably supported by the housing; a swash plate which is rotatable by the rotation of the drive shaft in the swash plate chamber; a link mechanism provided between the drive shaft and the swash plate and allowing the swash plate to change the inclination angle thereof with respect to the direction perpendicular to the axis of rotation of the drive shaft; a piston received to reciprocate in the cylinder bore; a conversion mechanism converting rotation of the swash plate into reciprocating movement of the piston in the cylinder bore for a stroke length that is determined by the inclination angle of the swash plate; a actuator allowing the swash plate to change the inclination angle of the swash plate; and a control mechanism controlling the actuator, wherein the cylinder bore includes a first cylinder bore provided on one side of the swash plate and a second cylinder bore on the other side of the swash plate, wherein the piston includes a first head that reciprocates in the first cylinder bore and forms a first compression chamber in the first cylinder bore and a second head that reciprocates in the second cylinder bore and forms a second compression chamber in the second cylinder bore, wherein the link mechanism is configured so that the top dead center position of the first head moves for a longer distance according to the change of the inclination angle of the swash plate than that of the second head, wherein the actuator includes an actuator body that is connected to the swash plate and partially movable in the direction of the axis of rotation of the drive shaft and a pressure control chamber that moves a part of the actuator body by the pressure in the pressure control chamber that is variable by the control mechanism, wherein the swash plate type variable displacement compressor further includes, a first suction flow passage through which the refrigerant gas drawn through the inlet port flows into the first compression chamber; a second suction flow passage through which the refrigerant gas drawn through the inlet port flows into the second compression chamber; a first suction valve mechanism provided in the first suction flow passage; and a second suction valve mechanism provided in the second suction flow passage, wherein the inner diameter of the first cylinder bore is smaller than that of the second cylinder bore, wherein the compressor has at least either a structure in which the first suction flow passage is different from the second suction flow passage and a structure in which the first suction valve mechanism is different from the second suction valve mechanism so that the refrigerant is drawn easily through the inlet port into the first compression chamber as compared to the case that the refrigerant gas is drawn through the inlet port into the second compression chamber.
 2. The swash plate type variable displacement compressor according to claim 1, wherein the suction chamber further includes: a first suction chamber provided adjacent to the first compression chamber; and a second suction chamber provided adjacent to the second compression chamber, wherein the first suction flow passage has a first suction passage through which the inlet port is in communication with the first suction chamber, wherein the second suction flow passage has the first suction passage, the first suction chamber, the swash plate chamber, a first communication passage through which the first suction chamber and the swash plate chamber are in communication with each other and a second communication passage through which the swash plate chamber and the second suction chamber are in communication with each other.
 3. The swash plate type variable displacement compressor according to claim 2, wherein the actuator is mounted on the drive shaft in the swash plate chamber to be rotatable together with the drive shaft, wherein the actuator body includes a fixed member fixed on the drive shaft and a movable member that extends in the direction of the axis of rotation of the drive shaft, has a cylindrical shape, is connected to the swash plate, encloses the fixed member and is movable in the direction of the axis of rotation of the drive shaft, wherein the pressure control chamber is formed between the fixed member and the movable member and separated from the swash plate chamber, wherein the pressure control chamber moves the movable member so that the swash plate increases its inclination angle with an increase of the volume of the pressure control chamber.
 4. The swash plate type variable displacement compressor according to claim 1, wherein the suction chamber includes: a first suction chamber provided adjacent to the first compression chamber; and a second suction chamber provided adjacent to the second compression chamber, wherein the first suction flow passage is formed in the housing and has a first suction hole through which the first compression chamber is in communication with the first suction chamber, wherein the second suction flow passage is formed in the housing and has a second suction hole through which the second compression chamber is in communication with the second suction chamber, wherein the first suction valve mechanism has a first suction reed valve that opens and closes the first suction hole according to the pressure difference between the first compression chamber and the first suction chamber, wherein the second suction valve mechanism has a second suction reed valve that opens and closes the second suction hole according to the pressure difference between the second compression chamber and the second suction chamber, wherein the first suction hole and the second suction hole are formed to have the same opening area, wherein the first suction reed valve is thinner than the second suction reed valve.
 5. The swash plate type variable displacement compressor according to claim 1, wherein the suction chamber includes: a first suction chamber provided adjacent to the first compression chamber; and a second suction chamber provided adjacent to the second compression chamber, wherein the first suction flow passage is formed in the housing and has a first suction hole through which the first compression chamber is in communication with the first suction chamber, wherein the second suction flow passage is formed in the housing and has a second suction hole through which the second compression chamber is in communication with the second suction chamber, wherein the first suction valve mechanism has a first suction reed valve that opens and closes the first suction hole according to the pressure difference between the first compression chamber and the first suction chamber, wherein the second suction valve mechanism has a second suction reed valve that opens and closes the second suction hole according to the pressure difference between the second compression chamber and the second suction chamber, wherein the first suction reed valve and the second suction reed valve are formed to have the same thickness, wherein the inner diameter of the first suction hole is larger than that of the second suction hole.
 6. The swash plate type variable displacement compressor according to claim 1, wherein the suction chamber includes: a first suction chamber provided adjacent to the first compression chamber; and a second suction chamber provided adjacent to the second compression chamber, wherein the first suction flow passage is formed in the housing and has a first suction hole through which the first compression chamber is in communication with the first suction chamber, wherein the second suction flow passage is formed in the housing and has a second suction hole through which the second compression chamber is in communication with the second suction chamber, wherein the first suction valve mechanism has a first suction reed valve that opens and closes the first suction hole according to the pressure difference between the first compression chamber and the first suction chamber, wherein the second suction valve mechanism has a second suction reed valve that opens and closes the second suction hole according to the pressure difference between the second compression chamber and the second suction chamber, wherein the first suction hole and the second suction hole are formed to have the same opening area, wherein the first suction reed valve and the second suction reed valve are formed to have the same thickness, wherein the first suction reed valve is bent larger than the second suction reed valve.
 7. The swash plate type variable displacement compressor according to claim 1, wherein the inner diameter of the first suction flow passage is larger than that of the second suction flow passage.
 8. The swash plate type variable displacement compressor according to claim 1, wherein the overall length of the first suction flow passage is shorter than that of the second suction flow passage.
 9. The swash plate type variable displacement compressor according to claim 1, wherein the suction chamber includes: a first suction chamber provided adjacent to the first compression chamber; and a second suction chamber provided adjacent to the second compression chamber, wherein the first suction flow passage is formed in the housing and has a first suction hole through which the first compression chamber is in communication with the first suction chamber, wherein the second suction flow passage is formed in the housing and has a second suction hole through which the second compression chamber is in communication with the second suction chamber, wherein the first suction valve mechanism has a rotating valve through which the first compression chamber in suction process is in communication with the first suction chamber with the rotation of the drive shaft, wherein the second suction valve mechanism has a suction reed valve that opens and closes the second suction hole according to the pressure difference between the second compression chamber and the second suction chamber. 